The present invention relates to a flush bolt mechanism for latching the inactive one of a pair of swinging doors.
Flush bolt mechanisms are known in the prior art, as shown, for example, in U.S. Pat. Nos. 2,034,570 and 3,578,369. These references show devices that have served to meet, in part, the needs of industry, although they are not fully satisfactory to meet existing requirements. Not only is it necessary that the flush bolt mechanism function to bolt the closed inactive door when the other of a pair of swinging doors is closed, but it is also desirable that the flush bolt mechanism function in a most satisfactory manner so that (1) it has a long and trouble-free life; (2) it will prevent retraction of the bolt when the flush bolt mechanism is subjected to heat conditions which are likely to cause buckling of the doors; (3) it will allow retraction of the bolt when forces of a predetermined magnitude are applied to the inactive door but not when the flush bolt mechanism has been subjected to the foregoing heat conditions; (4) damage is prevented to its components, such as its latch bolt, its actuator cam or the like, where the doors may become damaged or warped during usage that prevents proper alignment of the latch bolt with the keeper; and/or (5) it requires a force applied to the active door when closing the latter of only a relatively small preselected magnitude to drive the latch bolt home into the keeper. These and other needs which will not be discussed here are not satisfactorily met by the prior art.